Journal of Applied Mathematics and Physics, 2014, 2, 10-18
Published Online April 2014 in SciRes. http://www.scirp.org/journal/jamp
http://dx.doi.org/10.4236/jamp.2014.25002
How to cite this paper: Le Moyne, R. and Mastroianni, T. (2014) Fundamental Architecture and Analysis of an Antimatter
Ultra-Intense Laser Derived Pulsed Space Propulsion System. Journal of Applied Mathematics and Physics, 2, 10-18.
http://dx.doi.org/10.4236/jamp.2014.25002
Fundamental Architecture and Analysis of
an Antimatter Ultra-Intense Laser Derived
Pulsed Space Propulsion System
Robert Le Moyne1, Timothy Mastroianni2
1Independent Author (Senior Member AIAA & Senior Member IEEE), Running Springs, California, USA
2Independent Author, Pittsburgh, Pennsylvania, USA
Email: rlemoyne07@gmail.com
Received Dec emb er 2013
Abstract
Antimatter has been generated in large quantities by the Lawrence Livermore National Laborato-
ry Titan laser. The Titan laser is an ultra-intense laser system on the order of approximately
1020W/cm2 with pulse durations of roughly 1ps. With the Titan laser incident on a high atomic
number target, such as gold, antimatter on the scale of 2 × 1010 positrons are generated. Roughly
90% of the generated positrons are ejected anisotropic and aft to the respective target. The me-
chanisms for the laser-derived positron antimatter generation involve electron interaction with
the nuclei based on bremsstrahlung photons that yield electron-positron pairs as a consequence
of the Bethe-Heitler process, which predominates the Trident process. Given the constraints of the
current and near future technology space, a pulsed space propulsion configuration is advocated
for antimatter derived space propulsion, similar in concept to pulsed radioisotope propulsion.
Antimatter is generated through an ultra-intense laser on the scale of a Titan laser incident on a
gold target and annihilated in a closed chamber, representative of a combustion chamber. Upon
reaching a temperature threshold, the closed chamber opens, producing a pulse of thrust. The im-
plication of the pulsed space propulsion antimatter architecture is that the energy source for the
antimatter propulsion system can be decoupled from the actual spacecraft. In contrast to conven-
tional chemical propulsion systems, which require storage of its respective propulsive chemical
potential energy, the proposed antimatter propulsion architecture may have the energy source at
a disparate location from the spacecraft. The ultra-intense laser could convey its laser energy over
a distance to the actual spacecraft equipped with the positron antimatter pulsed space propulsion
system. Hydrogen is considered as the propulsive fluid, in light of its low molecular weight. Fun-
damental analysis is applied to preliminarily define the performance of the positron antimatter
derived pulsed space propulsion system. The fundamental performance analysis of the antimatter
pulsed space propulsion system successfully reveals the architecture is viable for further evalua-
tion.
Keywords
Ultra-Intense Laser, Antimatter, Positro n, Antimatter Propulsion, Antimatter Generation, Space
Propulsion
R. Le Moyne, T. Mastroianni
11
1. Introduction
The progressive evolution of fundamental science enables a novel architecture for antimatter propulsion. Rather
than incorporating traditional concepts which require evolution of other technologies, such as magnetic con-
finement or geometric constraints that inherently would require assembling in low earth orbit conditions; the
proposed architecture for antimatter propulsion may be readily tested and evaluated given the current technology
space. The antimatter propulsion concept incorporates a pulsed space propulsion format, which is far more feas-
ible than that of a steady state antimatter propulsion system. The positron antimatter pulsed space propulsion
architecture incorporates the current technology readiness involving the application of ultra-intense lasers. The
positron antimatter pulsed space propulsion architecture is envisioned for small spacecraft primary maneuvering
and attitude control.
Roughly a quarter of a century ago a conceptual design for an antimatter rocket based combined cycle was
promoted. However, viable antimatter production and storage technologies were and are currently unavailable
for such a conceptual design [1]. Steady state architecture incorporating antimatter generation from ultra-intense
lasers for ramjet applications has been successfully proposed by LeMoyne. The storage requirements are also
alleviated as antimatter, in the form of positrons, are only generated by the incidence of an ultra-intense laser
[2].
The capacity to generate significant quantities of positron antimatter as a consequence of ultra-intense lasers
has steadily progressed over the course of approximately four decades [3-5]. Current ultra-intense laser applica-
tions have demonstrated the ability to generate on demand and in-situ antimatter with laser incidence on a high
atomic number target, such as gold [4] [5]. However, the pulse rate requirement for steady state applications
warrants future evolution of ultra-intense laser technology.
The pulsed space propulsion condition alleviates the need for future ultra-intense laser pulse rate technology
evolution. Pulsed propulsion has been proposed for other configurations of non-chemical propulsion. For exam-
ple radioactive isotopes with protracted half-lives can accumulate thermal energy as a consequence of radioac-
tive decay. Upon the acquisition of a stored thermal threshold, the pulsed space propulsion system releases ac-
cumulated propulsive force [6] [7].
A fundamental performance analysis of positron antimatter laser derived pulsed space propulsion is estab-
lished. The fundamental performance analysis incorporates isentropic and energy balance relations. The positron
antimatter laser derived pulsed space propulsion application involves an ultra-intense laser incident on a gold
target for the generation of antimatter. The generated antimatter annihilates to accumulate thermal energy for the
propulsive thrust. Prior to the performance analysis and propulsion system description, the foundation for posi-
tron antimatter generation from the incidence of ultra-intense lasers is presented. Contrast of the proposed archi-
tecture to previous antimatter propulsion systems is established.
Appreciable on-spacecraft production and storage of antimatter may affect the consequence of escalated
system complexity. By contrast the proposed architecture for pulsed positron antimatter space propulsion
conveys laser energy to a target on the propulsion system, thereby decoupling the laser energy source from the
spacecraft. The proposed architecture also generates antimatter on demand and in-situ to the pulsed space
propulsion system, negating the complexity of antimatter storage requirements.
2. Previous Antimatter Propulsion Architectures
Antimatter derived propulsion has been a topic of interest for aerospace propulsion applications, in light of its
energy density. Antimatter-matter annihilation constitutes the greatest liberation of energy available [8]. One
gram of antimatter is comparable to the amount of energy stored in 23 Space Shuttle External Tanks [9] [10]. An
important consideration prior to addressing previous theoretical antimatter propulsion architectures is the dispar-
ity between the positron and the antiproton.
The positron and the antiproton constitute two different classes of antimatter. The positron annihilates with an
accompanying electron, yielding two gamma ray photons on the scale of 1.02 MeV [11-13]. The positron was
discovered in 1936 [14]. The antiproton annihilates with a proton yielding pions. Neutral pions quickly decay
into approximately 200 MeV by gamma radiation [15]. A portion of the resultant pions is charged [12] [15 ]-[18].
The decay pathway for the charged pions results in muons and neutrinos [16] [18]. However, pions decay after a
displacement about 21 meters [15] [19] [20] .
A major difference between positrons and antiprotons is in consideration of their generation and storage. Po-
R. Le Moyne, T. Mastroianni
12
sitrons can be produced by the incidence of an ultra-intense laser on a high atomic number target, such as gold.
Positrons can be generated on demand, with incidence of the ultra-intense laser on a gold target [2]-[5].
By contrast, particle accelerators generally produce antiprotons, such as through the facilities at CERN and
Fermi National Accelerator Laboratory. However, production is insufficient for envisioned propulsion applica-
tions. Also storage technology, although nascent, is insufficient for an antiproton antimatter propulsion applica-
tion [12].
Multiple conceptual architectures have been developed for the eventual goal of reaching antimatter propulsion
predominantly regarding antiprotons. During the 1980’s Dr. Forward of Hughes Research Laboratory proposed
a space propulsion system incorporating antimatter annihilation. The propulsion system incorporates the produc-
tion and storage of antimatter, local to the spacecraft. Proposed methodologies for the storage of antimatter in-
volve the use of electric fields, magnetic fields, and lasers. Intra-solar system applications would involve the
collection of solar energy [19]. However, the size and mass magnitude for generating antimatter from solar array
energy may diminish feasibility.
Other perspectives in antimatter propulsion were demonstrated in the 1980’s. Vulpetti proposed a liquid pro-
pellant thermal antimatter engine (LIPTHANE). The central theme to the LIPTHANE is the use of a heat con-
verter transmitter system that features a high atomic number, which incorporates gaseous xenon. According to
the design parameters, LIPTHANE requires an antiproton flux of 1017 per second. A major drawback cited is
that even laboratory settings fluxes are several orders of magnitude less than the LIPTHANE antiproton flux re-
quirements [21]. Also the LIPTHANE propulsion system lacks viable antiproton storage to support the neces-
sary flux.
Froning during 1988 proposed the use of antiproton antimatter for an air-breathing propulsion configuration.
A goal of the configuration was to reduce propellant mass requirements. The antiproton production strategy was
based on particle accelerator technology. An extrapolation of particle acceleration technology anticipated that by
roughly 2013, a sufficient amount of antiproton production threshold would be attained [1]. However, sufficient
antiproton production from particle accelerator technology has yet to be realized. Another issue with storing
large quantities of antimatter for a launch vehicle is the safety risk [1]. Also, human occupation of an antimatter
based launch vehicle applications involve the inherent risk of gamma radiation exposure [20].
Five identified architectures for antiproton derived antimatter propulsion are: solid core rockets, gaseous core
rockets, plasma core rockets, pion rockets, which direct the annihilation products by magnetic fields, and inters-
tellar ramjets. Regarding the solid, gaseous, and plasma core rockets the antiproton annihilation with matter
heats the propulsive fluid and is expanded by a nozzle. In the case of the plasma core rocket, a magnetic nozzle
is proposed [16]. The pion rocket is conceptualized on the principle that pions could be directed by magnetic
fields [16]-[18] [22]. The interstellar ramjet incorporates antiproton annihilation with available interstellar hy-
drogen [16] [17]. In order to support the quantity of antiprotons necessary for space propulsion missions, sub-
stantial advances in the supporting infrastructure for the production of antiproton antimatter are needed [17].
In light of the infrastructure limitations for antiproton production, the concept of using a limited portion of an-
ti-hydrogen antimatter to catalyze inertial fusion has been addressed. The antimatter would be injected into a
pellet consisting of deuterium and tritium or lithium deuteride. The pellet would comprise a hemisphere of fis-
sionable uranium or plutonium. The antimatter annihilation would induce temperature levels for localized fusion
[9] [23 ] [24]. Laser compression techniques have been suggested to augment the micro-fusion event. Such ar-
chitectures have been proposed for missions to Mars [25]. Even though antimatter requirements have been sub-
stantially reduced, antimatter catalyzed fusion has not been realized.
Winterberg offers a paradigm shift for the use of antimatter propulsion. Rather than using proton-antiproton
annihilation to heat a propulsive fluid for later expansion through a nozzle, the full conversion of the reaction
into gamma radiation is considered. The gamma radiation is developed into a coherent gamma ray laser beam.
The recoil of the laser beam pulse is transmitted to the spacecraft for propulsion. The novel propulsion concept
is considered appropriate for small spacecraft [26].
In consideration of the current perspective for approaching antimatter propulsion there exist substantial
challenges: antimatter production, storage, and operation. Enabling technologies, such as facilities with
sufficient production rate and antimatter storage systems, not only at the production facility but also appropriate
for the environment of the launch vehicle or spacecraft, are imperative for successful implementation [15] [22]
[27].
R. Le Moyne, T. Mastroianni
13
3. Ultra-İntense Laser Derived Antimatter
The proposed pulsed space propulsion configuration alleviates the technologically unfeasible requirements for
storage of antimatter. A recently realized strategy for generating antimatter is presented. The ultra-intense laser
is capable of generating antimatter in the form of positrons when incident on a high atomic number target, such
as gold. Therefore, the positron generation of antimatter occurs on demand as a consequence of the ultra-intense
laser striking the gold target. Simply shutting off the ultra-intense laser ceases antimatter production of positrons;
therefore greatly alleviating any antimatter storage requirement. LeMoyne successfully presented a similar con-
cept of antimatter propulsion for ramjet systems during 2012 [2]. In order to further alleviate ultra-intense laser
beam pulse requirements, the antimatter space propulsion incorporates a pulsed space propulsion configuration.
During the early 1970’s Shearer et al. published a conceptual strategy for the generation of positrons requiring
lasers on the scale of approximately 1020W/cm2 [3]. Three and a half decades later, Lawrence Livermore Na-
tional Laboratory experimentally demonstrated positron antimatter generation through an ultra-intense short
pulse laser incident on a high atomic number target, such as gold. The laser intensity was approximately 1020
W/cm2, using pulse duration on the order of 1ps. The ultra-intense laser pulse produced 2 × 1010 positrons. Ap-
proximately 90% of the positrons were discharged aft relative to the laser target. The laser target consisted of
roughly 1mm thick of gold [4] [5]. The ultra-intense laser pulse induced interaction between the electron and
nuclei that caused the generation of positron antimatter [4] [5] [28]. The Trident process and Bethe-Heitler
process are considered to be the basis for position antimatter generation using a high atomic number nuclei [4]
[28].
The Trident process utilizes a single step for generation of an antimatter positron. The electron directly
interacts with the nuclei to produce an electron-positron pair.
2eZeeZ
− +−
+→ ++
(1)
:e Positron
+
:e Electron
: ( )ZHigh atomic number nucleisuch as gold
[4] [28].
The Bethe-Heitler process comprises two steps. Fast electrons produce high-energy bremsstrahlung photons.
Then bremsstrahlung photons interact with the nuclei generating electron positron pairs.
eZ eZ
γ
−−
+ →++
(2)
ZeeZ
γ
+−
+→+ +
(3)
:Bremsstrahlung photons
γ
[4] [28].
The Bethe-Heitler process predominates for antimatter generation, since the Bethe-Heitler process cross sec-
tion is 100 times greater than the Trident process. Target thickness influences the prevalent electron-positron
pair generation process. The Bethe-Heitler process is significant for gold targets approximately 1mm thick. The
Trident process is the influential for gold targets that are about 3.5 micrometers thick [28].
The Lawrence Livermore National Laboratory Titan laser generated 21010 positrons through a ~1 ps pulse on
~1 mm gold target. The Titan laser intensity is ~1020 W/ cm2 using ~120 J of energy with a laser beam wave-
length of 1054 nm. The Bethe-Heitler process was identified as the most significant positron antimatter genera-
tion mechanism. The positron temperature was about 2 MeV. Approximately 10 times as many positrons were
discharged anisotropically normal to the aft relative the front [4] [5].
The implication of positron antimatter generated by an ultra-intense laser is that the energy source is decoup-
led from the propulsion system. Traditional spacecraft propulsion systems require the chemical energy source of
the propulsion system to be stored and integrated in to the spacecraft structure [29] [30]. The energy source for
the antimatter pulse propulsion concept could literally be a terrestrial nuclear reactor with an ultraintense laser
apparatus on the scale of a building conveying the ultra-intense laser beam to the targeted spacecraft at a re-
mote distance. The spacecraft with pulsed antimatter propulsion only requires a ~1 mm thick gold target.
Another notable attribute of the proposed antimatter pulsed space propulsion concept is that the ultra-intense
laser generates a series of pulses on the order of 1ps [4] [5]. By contrast published laser propelled light sail
configurations require a continuous 1PW of laser power [17]. Incorporating a pulsed space propulsion
architecture further alleviates the pulse requirements for the ultra-intense laser.
R. Le Moyne, T. Mastroianni
14
4. Pulsed Space Propulsion
The concept of pulsed space propulsion applications involves the progressive storage of thermal energy, by a
source such as radioactive decay. The storage of thermal energy occurs for a duration longer than the time span
of the propulsive thrust. Pulsed space propulsion designs are considered appropriate for small spacecraft primary
maneuvering and attitude control [6] [7]. As opposed to conventional radioactive decay, antimatter annihilation
provides the source of stored thermal energy.
5. Antimatter Derived Pulsed Space Propulsion Systemusing Ultra-İntense Laser
The envisioned antimatter pulsed space propulsion concept will incorporate a series of antimatter annihilation
pulses ultra-intense laser on the scale of a Titan laser incident on a ~1 mm thick gold target to generate positron
antimatter. The pulsed space propulsion system is under a closed chamber condition. The propulsive fluid is
progressively heated over a duration of time reaching a threshold temperature of 2500 K. Hydrogen is selected
as the propulsive fluid because of its low molecular weight. Upon attaining the 2500 K hydrogen propulsive
fluid temperature threshold the chamber opens generating a pulse of thrust.
In case the cross-section for positron antimatter annihilation is insufficient for hydrogen, a contingency con-
figuration is also considered. Tungsten is incorporated into the second design configuration, as its higher atomic
number and density may provide better annihilation cross-section properties. The second configuration would
incorporate a mass of tungsten internal to the closed chamber. The positron beam would annihilate with the
tungsten target (note that positron antimatter not antiprotons is considered), thereby heating the encompassing
propulsive hydrogen.
The energy source of the ultra-intense laser system is remote from the spacecraft equipped with the antimatter
pulsed space propulsion system. Therefore the spacecraft global architecture does not need to compensate for
large tanks of chemical potential energy or solar cells to specifically provide power to propulsion.
6. Fundamental Analysis and Performance Results
The objective of conducting fundamental analysis for the proposed antimatter pulsed space propulsion system is
to provide preliminary proof of concept. Higher fidelity analyses can be conducted later. The first goal is to es-
tablish an energy balance to attain 2500 K for the hydrogen fluid, and then determine the number of ultra-intense
laser pulses required to achieve the temperature threshold. The second goal is to determine steady state propul-
sion performance parameters.
The Lawrence Livermore National Laboratory ultra-intense Titan laser (1020 W/cm2) incorporates ~1 ps
pulses to generate 2 × 1010 positrons by laser incidence on a ~1 mm thick gold target. Approximately 90% of the
positrons are discharged anisotropic and aft to the laser target. The predominant mechanism is the Bethe-Heitler
process. Each ~1 ps pulse generates 1.8 × 1010 positrons to the aft of the laser target with roughly 2 MeV of ki-
netic energy [4] [5].
The rest mass of a positron and electron pair is 2 mc2 = 1.02 MeV. The electron rest mass (m) is equivalent to
the positron rest mass (m), and c is the speed of light. The kinetic energy of the positron is 2 MeV. Collisions are
assumed elastic, such that kinetic energy is conserved [11] [31]. The energy of a positron and electron annihila-
tion is 3.02 MeV [4] [5]. For each ultra-intense laser ~1 ps pulse, 8.71 × 106 kJ of energy is released aft to the
laser target.
The temperature prior to antimatter annihilation is assumed to be 300 K. Actual spacecraft reference tem-
peratures could be determined with more sophisticated techniques. Table 1 defines the closed chamber
conditions. Table 2 defi nes the material properties of tungsten and hydrogen [6] [30] [32] [33].
Table 1. Closed chamber conditions.
Hydrogen temperature (K) 2500
Hydrogen pressure (atm) 30
Chamber radius (m) 0.2
Hydrogen mass (kg) 0.01
Tungsten plate mass (kg) 0.1
R. Le Moyne, T. Mastroianni
15
Table 2. Material properties of tungsten and hydrogen at 2500 K.
Tungsten specific heat (kJ/kg-K) 0.18
Hydrogen constant pressure specific heat (kJ/kg-K) 17.9
Hydrogen specific heat ratio 1.2
Assuming an adiabatic surrounding of the chamber, the energy balance for determining the number of ultra-
intense laser pulses is defined as follows:
(4)
:
antimatter
QAntimatter heat addition
:
hydrogen
mMass ofhydrogen
()
:
p hydrogen
cSpecific heat ofhydrogen
:
tungsten
mMass oftungsten
:
tungsten
cSpecific heat oftungsten
:
f
TFinal temperature
:
i
TIntial temperature
The envisioned antimatter pulsed space propulsion concept consists of solely a closed chamber of hydrogen to
be heated by positron antimatter annihilation. Upon reaching a temperature threshold of 2500 K, a pulse of
thrust is generated. The required heat addition as a consequence of antimatter annihilation is 386 kJ. A total of
4.4 × 107 pulses from an ultra-intense laser would be required to generate a sufficient quantity of positron anti-
matter to heat hydrogen to 2500 K.
The contingency configuration incorporates a 0.1 kg plate of tungsten. The role of the tungsten plate is to
augment the functional cross section for positron antimatter annihilation. The addition of the tungsten plate in-
creases the required heat addition by 40 kJ for a total heat addition by antimatter annihilation to 426 kJ. Regard-
ing the contingency configuration, a total of 4.9 × 107 pulses from an ultra-intense laser would be required to
generate a sufficient quantity of positron antimatter to heat hydrogen to 2500 K.
Steady state fundamental propulsion analysis is incorporated to evaluate the propulsion performance parame-
ters of the proposed antimatter pulsed space propulsion system. Both the hydrogen only and contingency with
tungsten configuration consist of 10 grams of hydrogen that is pressurized to 30 atm at 2500 K, so their propul-
sion performance characteristics are equivalent. Based on a previous non-chemical space propulsion configura-
tion by LeMoyne, the mass flow is set to 1 gram/second [6]. During the steady state aspect of the propulsive ex-
pansion through a nozzle, the following relation, due to synthesis of isentropic relationships, is appropriate for
acquiring specific impulse:
( )
12
1
2
11
1
oe
sp o
RT p
Igp
γγ
γ
γ





= −








(5)
:
sp
ISpecificimpulse
:g Gravity
: RSpecific gas constant
:
o
TStagnation temperature ofchamber
:
o
pStagnation pressure ofchamber
:
e
pExit pressure
: Specific heat ra
γ
[29].
The above equation for deriving specific impulse assumes that the propulsive flow is expanding to a space
environment, and the exhaust pressure has a negligible contribution to the propulsive thrust. For the proposed
positron antimatter pulsed space propulsion system with positron generation through ultra-intense laser pulses,
the specific impulse is 1140 seconds. The thrust is 11.2 N.
The proposed propulsion configuration offers a robust non-chemical alternative for spacecraft. Incorporating a
pulsed space propulsion strategy, as opposed to a continuous mass flow system, alleviates the constraints on the
R. Le Moyne, T. Mastroianni
16
ultra-intense laser. Once the pulse of propulsive thrust is expelled, a new mass of hydrogen fluid can be heated
from a new series of ultra-intense laser pulses incident on a ~1 mm gold target that generates positron antimatter.
Preliminary investigations can be conducted by directing an ultra-intense laser on a ~1 mm gold target with the
generated positrons annihilating on a working fluid and imparting an energy source on the working fluid. Such
an experimental scenario could be evaluated in a laboratory environment with access to an ultra-intense laser.
7. Feasibility of Antimatter Pulsed Propulsion
The antimatter pulsed space propulsion constitutes the integration of newly demonstrated laboratory strategies
for generating considerable quantities of antimatter through ultra-intense lasers. Intuitively the ultra-intensity
laser strategy for antimatter generation could be integrated into a propulsion system. A pulsed space propulsion
strategy is incorporated to reduce requirements on the ultra-intense laser.
Other laser derived space propulsion systems have been conceptually developed. The perspective by Winter-
berg resembles the concept of the laser propelled light sail [26]. The laser propelled light sail uses a laser beam
to provide propulsion [8]. Light imparts momentum to the sail, as photons constitute particles of light. The pro-
posed sails functioning as receiver optics have diameters on the scale of 1000 km. Laser power requirements are
on the scope of a continuous 1 PW power budget [17]. Such power requirements are at the capacity level of all
of civilization [12]. In order to achieve the desired sub-relativistic velocities the propulsive laser beam must be
focused on the sail target for years of duration. Although inherently encumbered with substantial geometric and
power budget constrains, the laser powered light sail propulsion application has been published as a near term
technology [34].
The advanced concept of integrating ultra-intense laser technology as an applied physics breakthrough into a
practical aerospace application entails many unknowns and many design challenges. For example the limitations
of an ultra-intense laser on a gold target to generate positrons are unknown. The generation of positron anti-
matter does impart 120 J of ultra-intense laser energy on a ~1 mm gold target [4] [5]. Design challenges, such as
absorption of resultant antimatter annihilation radiation, optimization of flight characteristics, and analytical
consideration of the potentially relativistic effects of the resultant antimatter, should be addressed. A regenera-
tive cooling system to sustain a viable and sustainable temperature for the gold substrate versus the core
temperature of the hydrogen propulsive fluid should be applied. Regenerative cooling has been successfully
implemented in rocket propulsion systems numerous times [30]. Another strategy to address the thermal cons-
traints would be to apply a magnetic confinement system. The targeting of relativistic particles has been refined
to the point of integration into medical technology applications [13] [17] [20] [35] . The future evolutions of
ultra-intense lasers are expected, such as improvements in laser energy, pulse rate, and further convergence to
the direct process threshold of laser intensity.
8. Conclusions
Conventional perspectives in antimatter propulsion have previously advocated production by particle accelera-
tors and a storage system. The conventional approach has been identified as requiring considerable technological
investment to reach fruition. Ultra-intense lasers, such as the Lawrence Livermore National Laboratory Titan
laser, have been demonstrated for producing substantial amounts of positrons on the order of 2 × 1010 are gener-
ated by striking a high atomic number target, such as a ~1 mm gold target. Approximately 90% of the positrons
are ejected anisotropic and aft to the respective target.
The implications of the observed applied physics break through enable a new conceptual strategy for antimat-
ter propulsion using positrons. The positrons could be generated on demand as a function of the activation of the
ultra-intense laser, mitigating pending technologies for storage. The ultra-intense laser system could exist remote
from the spacecraft, enabling a decoupling of the propulsion system and its propulsive energy source.
The proposed spacecraft positron antimatter propulsion system incorporates a pulse-propulsion format to alle-
viate ultra-intense laser propulsion requirements. The propulsion applications store energy in hydrogen encased
in a closed chamber from positron annihilation. Two configurations are considered: a closed chamber consisting
of solely hydrogen that requires 4.4 × 107 pulses from an ultra-intense laser to reach a temperature of 2500 K for
the hydrogen propulsive fluid. A contingency configuration incorporates higher cross-section tungsten with the
hydrogen, and the alternative configuration would require 4.9 × 107 pulses from an ultra-intense laser to attain a
2500 K temperature for hydrogen. Upon reaching the 2500 K hydrogen temperature threshold, the chamber
R. Le Moyne, T. Mastroianni
17
opens generating a pulse of thrust. Fundamental analysis reveals that the positron antimatter propulsion system
provides a specific impulse of 1140 seconds with a corresponding thrust of 11.2 N. The positron antimatter
pulsed space propulsion architecture is suitable for small spacecraft primary maneuvering and attitude control
applications.
As the proposed positron antimatter pulsed space propulsion architecture synthesizes observation of applied
physics, many test and evaluation issues remain. For example, are there any limitations to the ultra-intense laser
incident on a gold target for a sustained pulse level? Ideally this publication brings more attention to a novel
approach for realizing a viable strategy for positron induced antimatter propulsion.
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